Electrical switch with contact elements serving as external terminals and as assembly fasteners



July 5, 1966 3,259,728

CHRlSTlAN-MARlE-GODEFROY DU TEMPLE DE ROUGEMONT ETAL ELECTRICAL SWITCH WITH CONTACT ELEMENTS SERVING AS EXTERNAL TERMINALS AND AS ASSEMBLY FASTENERS Filed June '7, 1963 United States Patent 8 Claims. (a. 200-166) This invention relates to an electric switching arrangement having fixed and moving contacts with sliding selector elements,

It is already known that such switching arrangements, usually controlled by a push-button, are extensively used in television and broadcasting receivers to perform the switching of weak-current circuits, of high or low frequency. They are also used for switching highor lowfrequency circuits generally, and for whatever application they are employed, it is endeavoured to obtain the lowest possible electrical resistance between the switch contacts, as well as a good time-stability of this resistance.

It is similarly desirable to ensure a very good behaviour of the components of such switching arrangements, in particular their contacts, in the presence of the high temperatures encountered in using solder baths or soldering irons, as well as a high resistance to shocks and repeated actuation.

Finally, it is important that the components should be capable of fabrication and assembly in automatic machines in order to reduce the cost.

The present invention enables the construction of switching arrangements satisfying these different conditions.

Button-controlled switching arrangements, in general, consist of an insulating casing carrying 'the fixed contacts, with which the moving contacts co-act, and they may also incorporate terminals or current taps for the different external circuits which are connected to the fixed contacts.

At the same time, this casing serves as a guide for a sliding selector element, also formed of insulating material, and which carries the moving contacts. For convenience in manufacture, the insulating casings carrying the fixed contacts are made in at least two parts, one of which is trough-shaped and guides the selector element in the manner of a slide on three sides, while the other part serves as a cover and a guide on the fourth side. It is to be understood, that these two parts must be firmly secured to each other by suitable separate connecting means, or by. connecting means incorporated in such parts.

In accordance with the present invention, the assembly of the two casing parts is effected by means of contacts which are themselves fixed, and not by separate joining means.

The present invention is, therefore, an electric switching arrangement comprising an insulating casing having a plurality of parts carrying fixed contacts and which houses a sliding selector element carrying movable contacts for coacting with the fixed contacts, the latter being formed of straight lengths of wire of circular cross-section inserted in holes made in opposed pairs in opposed parts of the casing, and the wires being crimped into contact with said parts to interconnect the parts, and the wires projecting from the casing on at least one side thereof.

The movable contacts are preferably made as thin, elastic blades of a conducting material, which are freely lodged in recesses made in the sides of the selector element opposite the fixed contacts, the recesses incorporat- 3,259,728 Patented July 5, 1966 "ice ing projecting bosses acting as pivot points for the contact blades, by which means the bearing force exerted by a movable contact on the two adjacent, fixed contacts, is exactly balanced.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which:

FIG. 1 is a perspective view of a double changeover switch according to the present invention;

FIG. 2 is a cross-sectional view of the same changeover switch through two of the fixed contacts;

FIG. 3 is an elevation partially in section of the casing of the same switch;

FIG. 4 is a perspective exploded view of the selector element carrying the movable contacts; and,

FIGS. 5, 6 and 7 show the combined action, in three different positions of the switch, of the movable and the fixed contacts.

The switching arrangement consists of a casing 2 of insulating material, which carries fixed contacts 4 to 4 and inside which there slides a selector element 6 carrying the movable contacts. The selector element 6 may be actuated in any suitable fashion, for instance by a push-button 8 and be continuously influenced by a spring 10.

The casing 2 consists of a channel-shaped slide 12 closed by a cover 14. The switching arrangement shown, is fitted for establishing two, characteristic connections between the fixed contacts: 4 with 4 and 4 with 4 (FIG. 7); or, 4 with 4 and 4 with 4 (FIG. 5); but it is understood that such a switching arrangement may combine a greater number of changeover switching positions, for instance four or six.

In accordance with the invention, the fixed contacts 4 to 4 are in the form of straight wires of circular crosssection, preferably of silver-plated copper, and are force fitted in opposing holes 16 and 18 made in the slide 12 and the cover 14.

At least one end of the wires projects outwards from the casing to form connecting terminals, but it is more advantageous as shown, to let both ends of the wire project from the casing to be able to connect them on either side of the switch casing. At the same time, the circular sec.- tion of the wire terminals enables their ready insertion in printed circuits on which the switching arrangement may be mounted.

The fixed contacts 4 to 4 connect the two parts 12 and 14 of the casing 2 and hold them locked by means of necks 20 without any additional fixing means. In practice, when assembling, a length of wire, say 4 is cut to the necessary size (FIG. 3) then clamped to form a first neck 20 and the end of the wire inserted in the first hole 16, which has an external, guiding bevel or countersink 16'; then in the second hole 18, which has an internal countersink 18'. As soon as the first neck 20 has abutted against the countersink 16', the second neck 20' is made, flush with the outer surface of the casing. The sensitive parts of the fixed contacts are thus protected from dust inside the casing and the crimping of the wires in the holes 16 and 18 prevents the flux or solder from penetrating to the conducting parts of the said, fixed contacts.

The movable contacts consist of a strip 22 or 22 of elastic metal preferably plated with a film of silver on the working face, which is folded back in a hooked shape. These movable contacts are freely inserted in notches 24 made in the selector element 6 and having a central boss 28 against which the shorter arm of the elastic blade 22 or 22' can bear. The selector element 6 which may incorporate a locking element (not shown) for securing it in either of its working positions, is moulded of a synthetic plastic material resistant to heat and abrasion, and with low dielectric losses.

The bosses 28 on the selector element 6 are so located that in each of the working positions (FIGS. and 7) of the switching arrangement, these bosses are substantially half-way between the adjacent, fixed contacts which are interconnected by the movable contact. Thus, in either of these positions, the contact pressure is perfectly balanced between the two, fixed contacts, and contact resist,- ances of the order of a few thousandths of an ohm, e.g. 0.003 ohm can be obtained, which are time-stable owing to the self-cleaning effect of the contacts sliding on each other. It will be seen that when passing the intermediate position shown in FIG. 6, the movable contacts 22 tilt slightly on the bosses 28, when their springs are compressed to the maximum, and then take up a new equilibrium position on the contacts 4 -4 (FIG. 7). It will be seen that in this, preferential form of the invention, comprising two, parallel longitudinal rows of fixed and movable contacts, the elasticity of the two opposed, movable contacts 22, 22' is counter-acting and sets up an automatic equilibrium condition, so that the contacts always remain clean, even if one of the spring blades 22 or 22 becomes weakened.

It is thus clear that a switching arrangement in accordance with the present invention comprises a reduced number of constituent elements and that it can be assembled very quickly and economically.

We claim:

1. An electric switching arrangement comprising an insulating casing having a plurality of parts carrying fixed contacts and which houses a sliding selector element carrying movable contacts for coacting with the fixed contacts, the latter being formed of straight lengths of wire of circular cross-section inserted in holes made in opposed pairs in opposed parts of the casing, and the wires being crimped into contact with said parts to interconnect the parts, and the wires projecting from the casing on at least one side thereof.

2. A switching arrangement in accordance with claim 1, wherein the insulating casing consists of a first part in the form of a slideway guiding the selector element on three of its sides, and a second part in the form of a cover guiding the selector element on its fourth side.

3. A switching arrangement in accordance with claim 1, wherein the opposed holes are of a diameter just suflicient to enable the wires to be push-fitted into said holes.

4. A switching arrangement in accordance with claim 1, wherein each of the movable contacts consists of an elastic blade of conducting material folded back upon itself in the form of a J or hook, and fitted in a longitudinal recess opposite the fixed contacts in the selector element, the recess having substantially at the centre of its length a supporting boss on which the shorter arm of the blade can pivot.

5. A switching arrangement in accordance with claim 1, in which the selector element is actuable by a push button thereon.

6. A switching arrangement in accordance with claim 1, in which the selector element is spring-biased.

7. An electric push-button switch comprising an elongated insulative casing having a rectangular lengthwise passageway therethrough, fixed contacts extending into said passageway and a selector slidably mounted in said passageway; said selector having a recess in at least one side thereof; at least one insulative boss on the selector extending into the recess; said selector carrying at least one rocking conductive element pivotal on said boss to wipe over and bridge contacts extending into said passageway.

8. An electric switch comprising an insulative housing containing relatively fixed and movable contact elements, said housing having one major face closed by a mating cover plate, and said fixed contact elements comprising wire-like conductors extending through close-fitting aligned sets of holes in said cover plate and in an opposite wall of the housing; said conductors extending be.- yond and outside of both said cover plate and said opposite wall, and being crimped adjacent the outer faces of said cover plate and said housing, whereby to secure said cover plate tightly against said housing.

References Cited by the Examiner UNITED STATES PATENTS 2,919,315 12/1950 Woofter 200-153 X 3,019,323 1/1962 Daniels 200164 X 3,072,757 1/1963 Gluck 20016 3,157,751 11/1964 Van den Berk 200 16 FOREIGN PATENTS 1,123,011 2/1962 Germany.

KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD A. GILHEANY, Examiner.

H. O. JONES, Assistant Examiner. 

1. AN ELECTRIC SWITCHING ARRANGEMENT COMPRISING AN INSULATING CASING HAVING A PLURALITY OF PARTS CARRYING FIXED CONTACTS AND WHICH HOUSES A SLIDING SELECTOR ELEMENT CARRYING MOVABLE CONTACTS FOR COACTING WITH THE FIXED CONTACTS, THE LATTER BEING FORMED OF STRAIGHT LENGTHS OF WIRE OF CIRCULAR CROSS-SECTION INSERTED IN HOLES MADE IN OPPOSED PAIRS IN 